Standardized A/V plugs and jacks are frequently used in consumer audio and telecommunication products. A/V plugs are familiar to most people, with the typical A/V plug comprising a series of electrically isolated cylindrical segments ending in a “tip” segment. More particularly, the body of the plug usually includes a sleeve, a ring, and a terminating tip, each providing contact points with the jack. These plug “contacts” are often referred to as poles.
While now commonly used in A/V applications, the sleeve-ring-tip plug nomenclature derives from the time when similarly styled plugs were used by operators of the early telephone switchboards. Indeed, such plugs commonly are referred to as “phone” plugs, although they are most commonly used in A/V applications, such as traditional domestic stereo and video equipment.
Many manufacturers, such as SWITCHCRAFT™, make standardized 2.5 mm and 3.5 mm audio plugs and jacks. Some of the most common uses for A/V plugs include termination of headphone/headset cables, microphone cables, guitar cables etc. A/V plugs are commonly used for both stereophonic and monaural devices.
For example, a stereo headset (FIG. 30A), such as might be plugged into a portable audio device (e.g. an MP3 player), typically includes an audio-plug terminated cable. In a common electrical configuration for stereophonic peripherals, the left speaker is wired to the plug tip, the right speaker is wired to the plug ring, and the plug sleeve serves as a ground connection (FIG. 30B). Of course, the audio device includes an audio jack with internal contacts arranged to selectively contact the sleeve, ring, and tip of the inserted plug (FIG. 30B).
Telephone headsets (FIG. 31A), as commonly used for telephony applications, do not require stereo sound, (although stereo audio may be used). Such headsets typically comprise a monaural speaker for audio output and a microphone for audio input. Again, the headset cable is typically terminated by a standardized 3-contact audio plug (FIG. 31B), with, for example, the microphone wired to the plug tip, the speaker wired to the plug ring, and headset ground wired to the sleeve of the plug (FIG. 31C). Again, the corresponding audio device will include a standardized audio jack that includes the appropriately arranged internal contacts.
Because the sizes and typical wiring schematic for such audio plug and jack combinations are relatively standardized, cross-manufacturer compatibility exists. For example, a headset manufacturer that adopts an industry standard audio plug for its various headset models can be relatively assured that those headsets will be compatible with audio devices from other manufacturers. Thus, there are significant advantages if manufacturers use standardized plug and jack configurations.
Although there are standards for these plugs, there are very many types of plugs, which can, depending on the function of the peripheral device for which they provide end-termination, each provide varying degrees of functionality for the electronic device. Although outwardly plugs may appear the same, the signalling down the plugs vary according to the functions that the peripheral device provides (FIG. 32)